// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/views/widget/root_view_targeter.h"

#include "ui/views/view.h"
#include "ui/views/view_targeter_delegate.h"
#include "ui/views/views_switches.h"
#include "ui/views/widget/root_view.h"
#include "ui/views/widget/widget.h"

namespace views {

RootViewTargeter::RootViewTargeter(ViewTargeterDelegate* delegate,
    internal::RootView* root_view)
    : ViewTargeter(delegate)
    , root_view_(root_view)
{
}

RootViewTargeter::~RootViewTargeter()
{
}

View* RootViewTargeter::FindTargetForGestureEvent(
    View* root,
    const ui::GestureEvent& gesture)
{
    CHECK_EQ(root, root_view_);

    // Return the default gesture handler if one is already set.
    if (root_view_->gesture_handler_) {
        CHECK(root_view_->gesture_handler_set_before_processing_);
        return root_view_->gesture_handler_;
    }

    // If rect-based targeting is enabled, use the gesture's bounding box to
    // determine the target. Otherwise use the center point of the gesture's
    // bounding box to determine the target.
    gfx::Rect rect(gesture.location(), gfx::Size(1, 1));
    if (views::switches::IsRectBasedTargetingEnabled() && !gesture.details().bounding_box().IsEmpty()) {
        // TODO(tdanderson): Pass in the bounding box to GetEventHandlerForRect()
        // once crbug.com/313392 is resolved.
        rect.set_size(gesture.details().bounding_box().size());
        rect.Offset(-rect.width() / 2, -rect.height() / 2);
    }

    return root->GetEffectiveViewTargeter()->TargetForRect(root, rect);
}

ui::EventTarget* RootViewTargeter::FindNextBestTargetForGestureEvent(
    ui::EventTarget* previous_target,
    const ui::GestureEvent& gesture)
{
    // ET_GESTURE_END events should only ever be targeted to the default
    // gesture handler set by a previous gesture, if one exists. Thus we do not
    // permit any re-targeting of ET_GESTURE_END events.
    if (gesture.type() == ui::ET_GESTURE_END)
        return NULL;

    // Prohibit re-targeting of gesture events (except for GESTURE_SCROLL_BEGIN
    // events) if the default gesture handler was set by the dispatch of a
    // previous gesture event.
    if (root_view_->gesture_handler_set_before_processing_ && gesture.type() != ui::ET_GESTURE_SCROLL_BEGIN) {
        return NULL;
    }

    // If |gesture_handler_| is NULL, it is either because the view was removed
    // from the tree by the previous dispatch of |gesture| or because |gesture| is
    // the GESTURE_END event corresponding to the removal of the last touch
    // point. In either case, no further re-targeting of |gesture| should be
    // permitted.
    if (!root_view_->gesture_handler_)
        return NULL;

    return previous_target->GetParentTarget();
}

} // namespace views
